other users unlocked it - it's proabably the problem of your version of the ROM. Use (U)[!]

2 Nov
19:40 2016

Downgrade skill by the time are considered damage ?

2 Nov
20:35 2016

Yeah. In this game downgrade=damage.

8 Nov
23:16 2016

HET

13 Nov
14:49 2016

A

15 Dec
19:00 2016

Its seems like you cant use continues to get The Professor's challenge. Why dont you mention this in description? Completing this without getting achievement is kind of frustrating.

15 Dec
20:47 2016

The description has a limit of maximum characters

11 May
1:35 2017

The professor challenge in HARDCORE mode is so dificult !

26 Jul
15:32 2017

Indeed it is... Going through the whole game again just to get hit or take damage by not getting hit is frustrating. And considering the game is nearly the length of SMB without warps, yeah... sucks being a completionist. lol.

13 Jan
13:43 2018

Redesigned the code of The Professor's Challenge to be possible to retry after losing a life (if you won't reach the checkpoint on the stage) or after using continue (after reaching the checkpoint of the stage, or the boss).